tag:theconversation.com,2011:/us/topics/hurricanes-2015-17447/articlesHurricanes 2015 – The Conversation2015-06-17T10:12:56Ztag:theconversation.com,2011:article/417132015-06-17T10:12:56Z2015-06-17T10:12:56ZWe need to change how and where we build to be ready for a future of more extreme weather<figure><img src="https://images.theconversation.com/files/85250/original/image-20150616-5829-if0b5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are more resilient ways to build in vulnerable areas.</span> <span class="attribution"><span class="source">Resilient Collective Housing', New Jersey Institute of Technology College of Architecture and Design studio project by Taryn Wefer and Naomi Patel. Instructors: Keith Krumwiede and Martina Decker</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The human and economic losses resulting from extreme weather events during the last several years vividly demonstrate the US’ historically shortsighted approach to development. The ill-advised, fast-paced construction of human settlements in <a href="http://dotearth.blogs.nytimes.com//2015/05/26/in-texas-the-race-to-develop-in-harms-way-outpaces-flood-risk-studies-and-warming-impacts/">low-lying, coastal and riverine environments</a> prone to flooding has long been the American way. From <a href="http://www.loc.gov/rr/news/topics/galveston.html">Galveston</a> to <a href="http://www.ucsusa.org/center-for-science-and-democracy/case-studies/hoboken-case-study.html#.VYA0FuuJnww">Hoboken</a>, we have laid out our grids and thrown up our houses with little regard for the consequences.</p>
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<span class="caption">Galveston, Texas in 1871, ‘but a waif of the ocean,…liable, at any moment, and certain, at no distant day, of being engulfed and submerged by the self-same power that gave it form.’</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Old_map-Galveston-1871.jpg">Camille N. Drie</a></span>
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<p>And the consequences can be devastating. Hurricane Sandy, which hit the East Coast in 2012 just one year after Hurricane Irene, another “100-year” storm, <a href="http://www.theatlantic.com/magazine/archive/2014/12/the-water-next-time/382242/">“filled up Hoboken like a bathtub.”</a> The storm’s impact all across the eastern seaboard was staggering: <a href="http://www.nhc.noaa.gov/data/tcr/AL182012_Sandy.pdf">147</a> people were killed, <a href="http://nca2014.globalchange.gov/highlights/regions/northeast">650,000</a> homes were damaged or destroyed, and <a href="http://www.oe.netl.doe.gov/docs/2012_SitRep20_Sandy_11072012_1000AM.pdf">8.5 million</a> residences lost power, some for weeks. In the end, the costs of the storm were pegged at over <a href="http://www.ncdc.noaa.gov/billions/events">US$60 billion</a>, making Sandy the second costliest natural disaster in US history after Hurricane Katrina in 2005.</p>
<p>Storms like Sandy are a harbinger of <a href="http://www.huffingtonpost.com/tom-zeller-jr/hurricane-sandy-link-to-climate-change_b_2059179.html">extreme weather events</a> to come as a result of climate change. Without concerted action, the costs, in lives and property, of future weather events will only multiply. It’s time we recognize not only that the climate is changing but that the development patterns that have hardly served us well in the past certainly won’t serve us well in the future. Changing course will require a reassessment of risks as they relate not only to <em>how</em> but also to <em>where</em> we build. In our larger, more densely populated regions and cities, massive storm protection projects are both necessary and economically viable, but in many places we would be much better served to move out of harm’s way.</p>
<h2>Climate change means more extreme weather events</h2>
<p>It’s beyond <a href="http://climate.nasa.gov/scientific-consensus/">dispute</a> that the planet is warming. The year 2014 was the warmest on record, and projections suggest that by 2100, average global temperatures could increase by between <a href="http://dels.nas.edu/resources/static-assets/materials-based-on-reports/reports-in-brief/Science-Report-Brief-final.pdf">2 and 11 Fahrenheit</a>. And with rising temperatures come rising sea levels. Globally, sea level <a href="http://www.epa.gov/climatechange/impacts-adaptation/coasts.html">rose 7 inches</a> during the 20th century, and projections for the 21st century are alarming, with estimates ranging from between <a href="http://nca2014.globalchange.gov/report/our-changing-climate/sea-level-rise">1 and 4 feet</a> globally.</p>
<p>The rise in global temperature and sea level has been accompanied by an increase in <a href="http://stateofthecoast.noaa.gov/insurance/welcome.html">flood events</a> and <a href="http://www.globalchange.gov/sites/globalchange/files/NCAJan11-2013-publicreviewdraft-chap2-climate.pdf">hurricane strength and activity</a> in the Atlantic. Since 1958, intense rainfall events have <a href="http://nca2014.globalchange.gov/report/our-changing-climate/heavy-downpours-increasing#intro-section-2">increased 71%</a> in the Northeast. This May, rainstorms in Texas dumped <a href="https://twitter.com/NWSFortWorth/status/604259036532326401">35 trillion gallons of water</a>, enough to cover the entire state to a depth of eight inches. Here again, <a href="http://nca2014.globalchange.gov/highlights/overview/climate-trends#intro-section">projections</a> don’t bode well for the future.</p>
<p>Along the Atlantic coast, stronger, wetter and <a href="http://nca2014.globalchange.gov/report/our-changing-climate/heavy-downpours-increasing#intro-section-2">more frequent storms</a> will result in ever-increasing levels of damage – especially when combined with <a href="http://www.epa.gov/climatechange/impacts-adaptation/coasts.html">bigger storm surges</a> due to rising sea levels, less protection due to the loss of storm-buffering wetlands and more exposure due to <a href="http://scenarios.globalchange.gov/scenarios/sea-level">increasing development</a> in low-lying areas.</p>
<p>Inland, an increase in <a href="http://nca2014.globalchange.gov/report/our-changing-climate/heavy-downpours-increasing#narrative-page-16569">extreme precipitation events</a> combined with more floodplain development and greater stormwater runoff over increasingly impervious ground surfaces will lead to more <a href="https://www.fas.org/sgp/crs/misc/R42850.pdf">frequent</a> and intense flooding.</p>
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<a href="https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85267/original/image-20150616-5816-1w47md9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Idea: let’s rethink building cities on floodplains.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/48722974@N07/4514870674">Department of Environment and Climate Change, NSW</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Dumb development decisions</h2>
<p>The <a href="http://www.cbo.gov/publication/50230">US Congressional Budget Office</a> predicts that the costs of hurricane damage in 2075 will double due to climate change alone and could increase fivefold with additional coastal development. And without significant changes in our land use policies, we will see additional development. Over the past 40 years, there’s been a <a href="http://stateofthecoast.noaa.gov/pop100yr/welcome.html">60% increase</a> nationally in the number of people living in coastal floodplains. And those floodplains are growing; with each new upstream development, another downstream site is compromised. Over the last 20 years, increased runoff from <a href="http://offcite.org/liquidation-in-the-face-of-water-extremes-houston-cannot-go-on-with-business-as-usual/">new development in Houston</a>, also known as the Bayou City, has added 55 square miles to the 100-year floodplain. </p>
<p>It should be clear by now that the rewards reaped from our current development patterns don’t outweigh the risks we face. In the past, we built our cities and settlements, not always wisely or well, with the assumption that the future would be similar to the past.</p>
<p>The evidence is now overwhelming that the future will be nothing like the past. But we continue, in many places, <a href="http://www.businessinsider.com/north-carolina-state-hiding-climate-science-2014-12#ixzz3bBDiTN00">to act as if it will</a>. Believing, perhaps, that if you ignore the science, the projections won’t come to pass, officials in <a href="http://www.weather.com/science/environment/news/north-carolina-pennsylvania-officials-ban-climate-change-global-warming">North Carolina, Pennsylvania</a> and <a href="http://www.miamiherald.com/news/state/florida/article12983720.html%23storylink=cpy">Florida</a> required that the term “climate change” be removed from official communications and state websites. Claiming “<a href="http://www.texasgop.org/wp-content/uploads/2014/06/2014-Platform-Final.pdf#page=8">‘climate change’ is a political agenda</a> which attempts to control every aspect of our lives,” Republican leaders in Texas “reject the use of this natural process to promote <a href="http://www.texasgop.org/wp-content/uploads/2014/06/2014-Platform-Final.pdf#page=33">more government regulation of the private economy.</a>”</p>
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<span class="caption">What happens after the floodwaters recede?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/chuckp/52326707">Chuck Patch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<h2>Subsidizing risk</h2>
<p>The problem with this logic, however, is that government action often tends to stimulate rather than impede private economic actions that both drive and increase our vulnerability to the impacts of climate change. In the United States, $18.5 billion in <a href="http://ecowatch.com/2014/07/16/subsidies-gas-oil-climate-change/">federal fossil fuel subsidies</a> not only hamper efforts to reduce greenhouse gas emissions but contribute directly to the expansion of the type of low-density sprawling development that increases the risks we face from extreme weather events, through increased runoff and the destruction of wetlands and open space.</p>
<p>The government further subsidizes risky development through the National Flood Insurance Program (<a href="https://www.fema.gov/national-flood-insurance-program">NFIP</a>), which is currently <a href="http://www.gao.gov/highrisk/national_flood_insurance/why_did_study%23t=0">$23 billion in debt</a> due to claims from Hurricanes Katrina and Sandy. By keeping the cost of insurance below real actuarial rates – <a href="https://www.cbo.gov/sites/default/files/11-04-floodinsurance.pdf">20%</a> of its <a href="http://bsa.nfipstat.fema.gov/reports/1011.htm">5 million</a> policies are explicitly subsidized – and by continuing to offer insurance on repetitive loss properties – one single-family home in New Jersey has filed <a href="http://www.njspotlight.com/stories/14/08/27/repetitive-flooding-means-recurring-problems-for-inland-new-jersey/">16 claims for a total of $1.3 million</a> — the NFIP shields property owners from the real risks to which they are exposed. In redistributing the costs of individual choices onto all taxpayers, the NFIP actively encourages development in vulnerable, high-risk areas. Recent <a href="https://theconversation.com/texas-floods-highlight-need-to-reform-key-insurance-program-42235">attempts to reform</a> the NFIP were thwarted by a coalition of <a href="http://www.njspotlight.com/stories/14/08/27/repetitive-flooding-means-recurring-problems-for-inland-new-jersey">coastal residents and the National Association of Homebuilders</a>.</p>
<p>We continue, in many cases, to let individual short-term interests trump collective long-term security, ignoring what climate science has proven with <a href="http://news.discovery.com/earth/global-warming/why-only-95-percent-certain-were-to-blame-130927.htm">95% certainty</a> – odds that any gambler would pray for.</p>
<h2>Embracing resilient design</h2>
<p>There are some positive signs of changing attitudes and approaches. With six innovative proposals funded in New York and New Jersey, the US Department of Housing and Urban Development’s <a href="http://www.rebuildbydesign.org/">Rebuild by Design</a> competition signals a willingness, at all levels of government, to invest in progressive, evidence-based resilient design efforts. Recognizing the densely populated region’s massive exposure to the threats posed by extreme weather, HUD is investing over <a href="http://portal.hud.gov/hudportal/HUD?src=/press/press_releases_media_advisories/2014/HUDNo_14-063">$900 million</a> in infrastructure-scale projects. They include the creation of a multipurpose berm and storm-buffering nature preserve in the Meadowlands of New Jersey and a multi-pronged protection plan including new bulkheads, stormwater pumps and green infrastructure in Hoboken.</p>
<p>Such projects are a wise investment. The <a href="http://www.nad.usace.army.mil/Portals/40/docs/NACCS/NACCS_main_report.pdf">Army Corps of Engineers</a> estimates that for every dollar spent on preparing for the anticipated effects of climate change – adapting, in other words – four to five are saved in post-disaster recovery and reconstruction costs. Unfortunately <a href="http://offcite.org/liquidation-in-the-face-of-water-extremes-houston-cannot-go-on-with-business-as-usual/">business goes on as usual</a> in many places, where bearing the <a href="https://www.morningstar.com/news/pr-news-wire/PRNews_20150603DA24960/economic-impact-of-texas-floods-could-be-up-to-550-million-bbva-compass-economists-say.html">expense of disaster recovery</a> trumps investing in preparedness.</p>
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<span class="caption">Consolidating development is one way to build smarter.</span>
<span class="attribution"><span class="source">'Resilient Collective Housing', New Jersey Institute of Technology College of Architecture and Design studio project by Taryn Wefer and Naomi Patel. Instructors: Keith Krumwiede and Martina Decker</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Smarter choices in where and how we build</h2>
<p>Rather than continuing to encourage shortsighted development practices, we should prioritize the development of denser, compact communities. Such communities offer <a href="http://www2.epa.gov/sites/production/files/documents/smart_growth_and_economic_success.pdf">economic</a>, <a href="http://www2.epa.gov/smart-growth/about-smart-growth#environmental">environmental</a> and social benefits that make them inherently more resilient than sprawling low-density developments. With their smaller footprint, such communities have <a href="http://www.smartgrowthamerica.org/issues/economic-prosperity/municipal-budgets/">lower infrastructure costs per capita</a> and provide for the preservation, or restoration, of natural habitats and storm-buffering wetlands. They also <a href="http://www.epa.gov/smartgrowth/pdf/location_efficiency_BTU.pdf">reduce energy consumption</a> and thus greenhouse gas emissions at both the household and neighborhood level. When properly designed, such developments balance the individual needs of each household with the collective needs of the larger neighborhood, encouraging a sense of mutual respect and responsibility that is critical to the resilience of the community.</p>
<p>We have the means to encourage adaption of this type. The voluntary buyout of flood-prone properties is particularly effective, from both a cost and resiliency perspective. Instead of continuing to subsidize flood insurance for properties in areas at risk of flooding — an estimated <a href="https://www.fas.org/sgp/crs/misc/R42850.pdf">one-third of all claims paid</a> through the NFIP are for repetitive loss properties — public funds should be used to acquire and restore the land to its natural state. A study done following a buyout of properties in Kentucky showed a return of <a href="http://www.martin.uky.edu/centers_research/Capstones_2011/White.pdf">$2.45</a> for every dollar invested in buyouts.</p>
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<a href="https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85124/original/image-20150615-5810-zqrq5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">It no longer makes sense to rebuild in the same places that keep getting hit.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jaxstrong/8270843634">JaxStrong</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>In addition to withdrawing from flood-prone areas, the creation of resilient, compact communities requires identifying and guiding development toward more opportune locations. In addition to having no adverse impact on existing floodplains, such locations should accommodate greater density while providing access to jobs, education and recreation through a variety of transportation choices. Unfortunately, current zoning often discourages compact development.</p>
<p>In concert with enacting zoning changes to promote more resilient development, communities can utilize a technique called <a href="http://www.njfuture.org/smart-growth-101/smart-growth-awards/2003-award/chesterfield/">transfer of development rights</a> (TDR). Most simply, TDR provides for the transferring of development rights from one location to another. Because zoning changes lower the development potential for some property owners while raising it for others, TDR essentially severs the right to develop land from the land itself. In this way, property owners seeking to build in areas where more development is desired would buy development rights from property owners in the area where less development is wanted.</p>
<h2>It’s time to wise up</h2>
<p>Each year brings more evidence of the human and economic impacts of climate change. It’s time that we stop throwing good money after bad. Rather than spending $25 million on PR campaigns to convince ourselves we’re <a href="http://www.newsworks.org/index.php/local/down-the-shore-justin-auciello/58112-everyone-has-an-opinion-about-njs-qstronger-than-the-stormq-ad-campaign-">“stronger than the storm,”</a> we should start making choices that prove we’re smarter. For while we can’t say when the next hurricane with the force of Sandy (or even greater force) will batter the Atlantic Coast or when extreme flooding will hit Texas, we do know that there will be a next time. And we’re still fundamentally unprepared for it. We can’t continue to bet against climate change; we’ll lose in the end.</p><img src="https://counter.theconversation.com/content/41713/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Krumwiede does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The climate is changing. Development patterns that have hardly served us well in the past certainly won’t serve us well in the future. Now is the time to adapt.Keith Krumwiede, Associate Professor of Architecture, New Jersey Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/420092015-06-05T14:25:28Z2015-06-05T14:25:28ZExtreme hurricanes show benefits of pooling catastrophic risks across states<figure><img src="https://images.theconversation.com/files/83982/original/image-20150604-3397-16x8bzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When will the next big one strike? </span> <span class="attribution"><span class="source">Hurricane via www.shutterstock.com</span></span></figcaption></figure><p><em>This article is part of The Conversation’s series this month on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>The official starting date for the Atlantic hurricane season was June 1, which happens to coincide with one of the major renewal dates for catastrophic wind reinsurance coverage. </p>
<p>Reinsurance is the process of insurers transferring risk they take on – by offering protection to homeowners and others – to other insurance companies (that is, reinsurers). It plays a critical role in the management of catastrophic risk, as it provides a mechanism for insurers to transfer some of their exposure and helps protect them when losses surge after extreme wind events like hurricanes. </p>
<p>Typically, this risk is spread further still, either by the insurer purchasing policies from multiple reinsurers or when a reinsurer sells part of the risk to other reinsurers operating in that market. </p>
<p>In addition to providing a mechanism for insurers to manage their exposure to catastrophic risk, catastrophe reinsurers potentially benefit through diversification by covering different types of catastrophes (such as from extreme winds, floods or earthquakes) and covering those risks across a wide geographic area. For the largest reinsurers, this could be on a global basis.</p>
<p>But these important benefits may be less valuable in a market where reinsurance pricing does not sufficiently reflect the risks. That’s been happening in recent years as the reinsurance market has experienced “soft” conditions – a decline in the pricing of catastrophic wind risk combined with ample reinsurance capacity. The trend has continued this year. </p>
<p>While lower prices provide obvious benefits to regular insurance companies (and potentially consumers) in the short to medium term, it also increases the likelihood of price spikes and a sharp drop in reinsurance capacity in the event of a very large catastrophic loss or a series of substantial shock losses. </p>
<p>The experience of the Florida market following the combined losses from the 2004 and 2005 hurricane seasons illustrates the potential problems when large shock losses result in significant price volatility. </p>
<p>The last significant hurricane event in Florida before that was Andrew in 1992. Typically, major hurricanes (category 3-5) <a href="http://www.nhc.noaa.gov/climo/images/return_mjrhurr.jpg">occur</a> once every 14 to 20 years across south Florida.</p>
<p>Following Hurricane Andrew, homeowners’ insurance showed small <a href="http://flains.org/fact-book-othermenu-38/904-property-insurance-background/2080-iii-key-facts-about-property-insurance.html">gains</a> in underwriting profitability in each of the 10 years prior to 2004 – when four major hurricanes hit the state from August 13 to September 26. </p>
<p>However, those underwriting gains <a href="http://www.myfloridacfo.com/pressoffice/documents/florida%20hurricanes%20take%20financial%20toll06.htm">were wiped out</a> after the market experienced almost US$36 billion in combined hurricane losses for 2004 and 2005. </p>
<p>Given the size of the losses, a jump in insurance rates was expected. But the magnitude was even greater due in part to substantial price increases from the reinsurance market. <a href="http://www.nytimes.com/2007/01/23/us/23florida.html?_r=0">Concerns</a> about affordability of insurance for property owners in Florida were one of the key issues in the 2006 gubernatorial election, and this led to a special legislative session on property insurance reform. </p>
<p>There also were <a href="http://www.insurancejournal.com/news/southeast/2006/05/04/67909.htm">calls</a> for a national solution through the <a href="http://www.myfloridacfo.com/hurricaneinsurancetaskforce/TaskforceRS2/draftlts6.pdf">creation</a> of a federal catastrophic wind risk pool, in which coverage for extreme wind events would be provided by the US government. While there was little support outside Florida for this type of approach at the time, the debate in the US about establishing a mechanism for insuring catastrophic wind risk at the national level has been ongoing and predates the substantial losses from the 2004 and 2005 hurricane seasons. </p>
<h2>Pooling the risks</h2>
<p>In order to better understand geographic diversification of catastrophic risk, two colleagues and I <a href="http://dx.doi.org/10.1057/gpp.2014.20">used</a> a catastrophe model and property data from the 2010 American Community Survey to calculate damage from tropical cyclone events (hurricanes and lesser tropical storms). We also looked at relevant causes of losses (wind, rain and storm surge) on property portfolios that ranged from single structures to an amalgamation of every residential exposure within the state of Florida to a larger risk pool of multiple combinations of coastal states in the southeastern US. </p>
<p>We wanted to understand whether and where diversification benefits accrued as risks were aggregated over an increasingly wide geographic area. We found that benefits began to accrue when the distance between exposures was around 140 nautical miles (about the average swath width of a tropical cyclone). </p>
<p>For the less severe but more frequent losses that result from hurricanes and tropical storms that strike once ever 20 to 25 years or less (known as the return period), there appeared to be no benefit of greater geographic diversification. </p>
<p>However, for less frequent, more severe events – those that have a return period of more than 25 years, including 1-in-100-year hurricanes like Katrina and Andrew – there were clear diversification benefits from spreading the risk over more states. Additionally, those gains increased with the return period. </p>
<p>The impact of these benefits becomes more meaningful when they are quantified. For example, the claims-paying capacity (how much capital would be needed to cover all anticipated losses) required for a 1-in-100-year event for the eight coastal states from Texas to Virginia, each operating in isolation, would be just over $130 billion. </p>
<p>But as a combined risk pool, such an event for the entire region is just over $71 billion, or $59 billion less. Based on these results, the risk pool requires significantly less capacity across time than would be required by treating each state in isolation.</p>
<h2>Benefits versus costs</h2>
<p>The most common argument against establishing such a risk pool is that it creates a subsidy for the higher-risk members of that particular pool. The <a href="http://www.insurancejournal.com/news/southeast/2006/05/04/67909.htm">debate</a> is not limited to property insurance; in Obamacare, for example, younger individuals subsidize older ones.</p>
<p>For catastrophic risk coverage more broadly, the question takes the form of: why should someone in the state of Alabama subsidize the catastrophic wind risk of a resident of Florida or Texas? Or why should inland residents subsidize those living on the coasts? </p>
<p>While the debate from these types of questions is important, it typically occurs in the absence of meaningful empirical evidence that compares the cost of subsidies with the benefits of pooling and potential reduction in taxpayer losses after catastrophe has occurred. </p>
<p>As our results indicate, those arguments become less valid as we look at longer return periods because each state in the pool that we evaluated benefits from geographic diversification. As such, we would argue that these benefits across time outweigh the subsidy costs. </p>
<p>As we begin the 2015 hurricane season, we do not know with certainty whether or not we will experience a major hurricane event this season or where it would occur. We do know, however, that the pooling of catastrophic risk – whether in a private market, through reinsurance, in a regional or national public pool or some combination – can provide meaningful benefits in terms of geographic diversification.</p><img src="https://counter.theconversation.com/content/42009/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Randy Dumm received a financial award from the International Insurance Society (Shin Excellence in Research award) for the research described in this paper. He is the Chairman of the Board of Sawgrass Mutual Insurance Company and he serves as an expert witness for a Florida based property and casualty insurer. He is a past member and Chair of the Florida Commission on Hurricane Loss Projection Methodology and he was a member of the State of Florida’s Task Force on Long-Term Solutions for Florida’s Hurricane Insurance Market. </span></em></p>A look at the Florida insurance market following the flurry of severe hurricanes in 2004-2005 shows that pooling risk can cut losses.Randy E Dumm, Hold Professor of Risk Management and Insurance, Florida State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/401412015-06-04T05:53:24Z2015-06-04T05:53:24ZShould I stay or should I go: timing affects hurricane evacuation decisions<p><em>This article is part of The Conversation’s 2015 series on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>In the US, the 2015 hurricane season begins against a backdrop of other recent extreme weather news. Texas floods and Midwest tornadoes remind us of what water and wind can do. We can take comfort from considerable improvement in hurricane forecast accuracy in recent years. But when a hurricane is gathering strength offshore, people in its possible line of fire still need to decide whether or not to evacuate to safer ground.</p>
<p>As a social scientist, I’ve been interested in what goes into the choice whether to stay or to go, and whether people will have time to leave if that’s what they choose to do. It’s a complex decision that can be a matter of life and death. Why do some people evacuate and some do not? We’re finding that timing can have a lot to do with it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=362&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=362&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=362&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=454&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=454&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83883/original/image-20150604-2929-u9qsjn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=454&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A hurricane’s storm surge can be deadly.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/au_tiger01/110282480">au_tiger01</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Getting out of a storm’s path saves lives</h2>
<p>Consider the comparison of lives lost due to Hurricanes Katrina and Sandy. <a href="http://www.nhc.noaa.gov/data/tcr/AL182012_Sandy.pdf">Forty-one people drowned</a> from Sandy’s <a href="http://www.nhc.noaa.gov/surge/">storm surge</a> and 31 others died from falling trees and other causes. Katrina killed more than <a href="http://www.nhc.noaa.gov/data/tcr/AL122005_Katrina.pdf">1,800 people</a>. Over half of the Mississippi evacuation zone residents <a href="http://dx.doi.org/10.3141/2312-10">heeded the call</a> and left ahead of Katrina. That compares with about 30% for Sandy, according to my own survey research.</p>
<p>Comparing populations between coastal Mississippi and New Jersey/New York, a storm like Katrina could have translated to many thousands of deaths if it had hit the New York metropolitan area.</p>
<p>It wasn’t evacuation that made a difference in the number of lives saved. The sobering conclusion is that it was just luck that Sandy, hitting a much more populous area, had weaker winds blowing over people trying to evacuate the day the storm arrived. But the next storm through could have much more intense winds. That potential scenario makes it crucial to examine why there was such a low evacuation rate for Sandy – and how to make sure a future situation would have a higher one. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83869/original/image-20150603-2935-57xrr0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Example of a storm surge inundation map for a hypothetical hurricane hitting Charleston, SC.</span>
<span class="attribution"><a class="source" href="http://www.nhc.noaa.gov/experimental/inundation/">NOAA National Hurricane Center</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What goes into the decision to leave</h2>
<p>Most <a href="http://dx.doi.org/10.1061/(ASCE)1527-6988(2007)8:3(69)">behavioral studies</a> show hurricane evacuation rates can be explained by a number of factors, including media communication of forecast risk, physical risk at a person’s location, demographics (for instance, people with young children are more likely to evacuate, while the elderly often find it harder to do so), and availability of transportation resources, as well as a place to go. </p>
<p>However these factors never explain more than half the variance in evacuation. The rest is the hard part, what psychologist Paul Slovic calls “<a href="http://dx.doi.org/10.1126/science.3563507">intuitive risk judgments</a>.” Certainly there are some people who believe they’ll be safe no matter what. But most people routinely do a good job of deciding to do things like buying insurance against big dangers that are not very likely to happen.</p>
<p>The problem for the public in hurricane evacuation is not the probability part; it’s the danger part, whether storm surge could actually happen to <em>me</em> and result in <em>my</em> death or loss of livelihood. It’s vital that everyone, politicians as well as the public, is educated about how <a href="http://www.nhc.noaa.gov/surge/StormSurgeCanBeDeadly10tips-single.pdf">storm surge works and the risks</a> affiliated with it. When people aren’t sure but get scared they will go ahead and evacuate, even when the result is unnecessary traffic gridlock, as happened in hurricanes Floyd and Rita. </p>
<p>So the problem for forecasters, media and authorities is threefold: make sure the people at risk know they are, make sure people who can safely stay home know that, and get those two groups of people informed far enough ahead of time that they can know what to do when evacuation orders come down. To accomplish these goals, precise locational information on surge risk is needed – such as will be provided by the new <a href="http://www.nhc.noaa.gov/experimental/inundation/">Potential Storm Surge Flooding Map</a> developed by the National Hurricane Center.</p>
<p>This kind of map can be made available up to 36 hours ahead of hurricane landfall once surge modelers know what the characteristics of the storm will be as it approaches land. Before that, an accurate forecast is not possible because location and height of storm surge is heavily dependent on the hurricane’s track, size and strength, as well as the configuration of near-shore bays and other water bodies, and underwater terrain where it hits.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83870/original/image-20150603-2966-bozvsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricane Ivan demonstrated how whether a storm hits during the daylight hours affects how effective evacuation is.</span>
<span class="attribution"><span class="source">Hugh Gladwin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>People need time</h2>
<p>Few studies have looked at what happens next, once people realize they need to evacuate. Timing appears to be a crucial factor. </p>
<p>Studies indicate that authorities need to allow a full 24 hours after definitive evacuation orders for people to get ready and <a href="http://www.safetylit.org/citations/index.php?fuseaction=citations.viewdetails&citationIds%5B%5D=citjournalarticle_55911_29">actually leave</a>. Preparing to go, coordinating work and family members, and organizing <a href="http://dx.doi.org/10.1016/j.trc.2014.02.015">transportation</a> can take a full day. And after that, evacuees may need 10 hours of daylight to travel before hurricane force winds arrive.</p>
<p><a href="http://coast.noaa.gov/hes/hes.html">Hurricane Evacuation Studies</a> are done by the US Army Corps of Engineers. These incorporate behavioral studies and traffic modeling to predict clearance times to get everyone out of evacuation zones, assuming good compliance with evacuation orders. Clearance times for the Miami area, for instance, run 20 to 30 hours, depending on the size of storm forecast. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83865/original/image-20150603-2935-12x6qug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chart of when people in NJ and NY evacuated ahead of Hurricane Sandy making landfall on Monday evening.</span>
<span class="attribution"><span class="source">Hugh Gladwin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>As noted above, this 24+10 hour time frame is approximately how far out hurricane forecasters can <a href="https://theconversation.com/hurricane-forecast-accuracy-is-improving-but-dont-overly-focus-on-the-skinny-black-line-40794">accurately predict</a> where storm surge impact is likely to be. So in this case the limits of our forecasting technology fit with the limits of human preparation. The trouble comes in if the 10-hour period for travel turns out to be at night. Postponing departure until morning, which is human nature, means evacuating and traveling through tropical storm force or higher winds. Hurricanes Ivan and Sandy both fit this scenario, with people evacuating through tropical storm force winds. Hurricanes Katrina and Andrew did not, because their time frames were 12 hours different, allowing people to travel during daylight before the storms arrived in the early hours of the morning.</p>
<p>The time potentially needed for evacuation thus makes it essential that the public knows what the worst case for <a href="http://www.nhc.noaa.gov/surge/">storm surge</a> could be for them and is alerted to the need to plan for a possible evacuation order. The National Hurricane Center has maps of <a href="http://www.nhc.noaa.gov/surge/products.php">worst-case storm surge scenarios</a> for any configuration of possible hurricanes along the US coastline. Emergency managers use these routinely, but media and authorities need to communicate to the public where people must be alert to risk and also where people can know they will not have to evacuate in any hurricane scenario.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83874/original/image-20150603-2943-5k3yn6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Let’s hit the road.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/23122254@N07/7162813132">Billy Metcalf Photography</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>What we need to hear, and when</h2>
<p>Emergency managers are charged with ensuring the safety of the population. “Prepare for the worst” is probably a good philosophy in most circumstances, but not in the case of evacuation for a hurricane many days away, when the cost of mobilizing is high and the probability of it being needed is very low. The government and media also grapple with not wanting to be unnecessarily alarmist. The correct philosophy is “know what the worst case could be and be prepared to face it if it comes to pass.” </p>
<p>When an evacuation order is issued, it’s usually in a very compressed time frame – but that’s ok as long as people are prepared. If people plan three to five days ahead, knowing that there is a small but real chance they will be asked to evacuate and a small but real chance of death if they do not, they can be ready when the definitive order comes in.</p><img src="https://counter.theconversation.com/content/40141/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hugh Gladwin consults for SocResearch Miami on hurricane behavior studies. He has applied for and received National Science Foundation grants to study disasters.</span></em></p>Hurricanes can be deadly to those in their path. Officials don’t want to unnecessarily alarm before solid forecasts are in place, but residents need enough time to prepare and heed evacuation orders.Hugh Gladwin, Associate Professor of Global and Sociocultural Studies, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/401372015-06-03T10:28:45Z2015-06-03T10:28:45ZThere are better ways to quantify how big and bad a hurricane is<figure><img src="https://images.theconversation.com/files/83719/original/image-20150602-19255-1h35mg0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Only a Category 1 at landfall, Hurricane Irene had plenty of energy.</span> <span class="attribution"><a class="source" href="http://www.hwind.co/legacy_data/Products/Operational/2011/AL092011/0826/2230/AL092011_0826_2230_contour08.png">H*wind</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><em>This article is part of The Conversation’s series this month on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>When a hurricane is coming in off the Atlantic, about to make landfall, you’re bound to hear talk of what category the storm is. Watch out, it’s a Category 1, or batten down the hatches, it’s a Category 5.</p>
<p>These numbers are taken from the Saffir-Simpson hurricane wind scale (<a href="http://www.nhc.noaa.gov/aboutsshws.php">SS</a>), which depends only on maximum sustained surface wind speed, as measured 10 meters above the ground at one point inside the tropical cyclone. Category 5 is the strongest storm, with winds over 157 mph. The Saffir-Simpson measure of intensity is highly local in time and space because it focuses on a speed sustained for a minute at one single location. But this scale has the advantage of a simple 1-5 range, and it’s popular with the media and the public.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83720/original/image-20150602-19255-b8l9ui.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">But what does it all mean for me and my neighborhood?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/apes_abroad/5115797707">Colin and Sarah Northway</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The desire to distill hurricanes down to a single number or index is strong – but the task is quite challenging. Some indices aim to boil each June through November season’s total hurricane activity – including quantity, intensities and lifespans – down to one number; that can be useful for climate scientists interested in long-term tracking. Other indices apply to a hurricane at any time during the storm’s life cycle, and are useful for communicating destructive potential. The Saffir-Simpson scale is one of these; but unfortunately, in its case, the single number is inadequate, particularly since evacuation decisions usually need to take into account the potential threats from wave and storm surge inundation – which it doesn’t consider.</p>
<p>We’ve worked on a new way to project a hurricane’s strength that takes into account the size of the tropical cyclone. Our method is better because it considers the distribution of the surface wind speed around the center of the storm, unlike the traditional Saffir-Simpson scale that depends on a point measurement of the maximum wind speed. By measuring total energy, we can make a better prediction as to destructive potential than if we’re just looking at wind speed at a single point location.</p>
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<figcaption>
<span class="caption">Lots of data feed into the IKE index.</span>
<span class="attribution"><a class="source" href="http://www.hwind.co/legacy_data/wind.php?year=2011">H*wind</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>More variables make a scale more valuable</h2>
<p>What do you really want to know when a hurricane is headed your way? Probably how much damage you can expect to your area, whether from wind, waves or some combination.</p>
<p>This is why the Integrated Kinetic Energy (IKE) index <a href="http://dx.doi.org/10.1175/BAMS-88-4-513">is an improvement</a> over the Saffir-Simpson scale most laypeople are used to. It goes beyond wind speed to take size into account. Reconnaissance aircraft flown routinely by the US Air Force and NOAA measure wind speeds for most tropical cyclones that are close to or bound for US shores. You can think of a hurricane as having concentric circles of various wind speeds. IKE is a way to sum up the square of the winds blowing around the center of the storm. We divide the storm into quadrants and square the strength of the winds in each until we reach the point toward the perimeter of the hurricane where they’re measuring 40 mph or less. That’s the cutoff for tropical storm force winds, and the National Hurricane Center stops measuring the radius of winds at that point.</p>
<p>For two comparable storms with similar intensity, the one with a larger span outward from the center of 40 mph winds and greater will have higher IKE. So IKE is a better representation of the overall destructive potential of a hurricane than just intensity. Moreover, IKE scales with the wind stress on the ocean surface, which is the primary reason for storm-generated surge and waves.</p>
<p>We’ve introduced Track Integrated Kinetic Energy (<a href="http://dx.doi.org/10.1175/MWR-D-12-00349.1">TIKE</a>) as a way to sum up the Integrated Kinetic Energy over a storm’s lifespan. It includes the size of the wind field – basically the diameter of the hurricane – along with the intensity and lifespan of the storm. Because TIKE provides a single measure that combines these three factors for each storm, it allows us to track variability over the Atlantic hurricane season in a more complete manner.</p>
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<a href="https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83707/original/image-20150602-19235-e7n8iz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Category 5 Camille vs Category 3 Katrina at landfall.</span>
<span class="attribution"><a class="source" href="http://www.wunderground.com/hurricane/surge_details.asp">NOAA Hurricane Research Division</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Index numbers versus destruction on the ground</h2>
<p>A historical comparison of high-impact events can help demonstrate why Hurricane Katrina – a Saffir-Simpson scale Category 3 storm at landfall in Mississippi – brought a storm surge that exceeded the previous benchmark for coastal Mississippi, set by SS Category 5 Hurricane Camille. Katrina’s wind field displayed IKE (120 Terrajoules) values twice as large as Camille (60 Terrajoules), despite having a lower intensity. Unfortunately many residents based their preparations on Camille’s historical high-water marks and paid the price, with a resident <a href="http://www.aoml.noaa.gov/hrd/Powell/BAMS_IKE_Paper_final.pdf">quoted</a> in the Biloxi, Mississippi Sun Herald after the 2005 storm saying “Camille killed more people yesterday than it did in 1969.” Despite its lower intensity, Katrina’s winds covered a much larger area than Camille, allowing it to do more damage, mostly via widespread coastal flooding.</p>
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<a href="https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83730/original/image-20150602-19235-1llf7mz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricane Sandy didn’t need to be more than Category 1 to do major damage in New York City.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/timothykrause/8143636522">Timothy Krause</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<p>The advantages of IKE become even more apparent when we look at recent low-intensity, high-impact events. In 2012, Hurricane Sandy’s huge wind field generated IKE values over 300 TJ, good enough for a 5.8 reading (out of 6) on the Powell-Reinhold (PR) surge <a href="http://www.aoml.noaa.gov/hrd/ike/Files/UJNR_IKE_2009.pdf">destructive potential scale</a> which one of us originated, while the Saffir-Simpson scale reading was only a 1. And Sandy wasn’t an outlier. Hurricane Irene, which affected North Carolina and New England in 2011, reached just over 115 TJ with a 5.1 PR rating, and Hurricane Ike, which struck Texas in 2008, had a wind field that filled the Gulf of Mexico with IKE of 150 TJ and 5.2 on the PR scale. But Irene and Ike on the SS scale rated just 1 and 2, respectively.</p>
<p>As Ike approached Texas, Mississippi’s Sun Herald took the unprecedented step of <a href="http://www.aoml.noaa.gov/hrd/ike/Files/mcclatchydc_52364.pdf">issuing an editorial warning</a> Texas residents to not be fooled by the low SS rating of Hurricane Ike, citing the “developing science of integrated kinetic energy.”</p>
<h2>Refining the measurements</h2>
<p>Currently we’re working on a hurricane wind <a href="http://www.hwind.co/">analysis archive</a> generated from a collection of wind data for a given storm from a variety of sources, including satellites, aircraft and radar. As this data set grows, it can help compute TIKE and assess its year-to-year variations. There are also new planned US <a href="http://science.nasa.gov/missions/cygnss/">satellite missions</a> that will attempt to measure hurricane surface winds, which could provide robust global estimates of IKE as well.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/qu_zMxJtyz0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">ISS-RapidScat uses radar to measure the surface of the ocean.</span></figcaption>
</figure>
<p>There’s even a NASA instrument aboard the International Space Station called <a href="http://www.jpl.nasa.gov/missions/iss-rapidscat/">RapidScat</a> that can sample a hurricane’s winds using the radar return from tiny “capillary waves” found atop wind waves in the ocean. Unfortunately, due to other demands for the precious space station real estate, RapidScat may only be available for a limited time.</p>
<p>Indexing tropical cyclone activity has been found valuable for communicating a complex phenomenon rapidly to the population in harm’s way. We are continuing to find ways to improve these indices to better represent the damage that some of these land-falling hurricanes cause, and IKE is one such attempt. With rapid coastal development around the world, the number of people and amount of property vulnerable to such extreme weather events is growing. Attempts to characterize these weather phenomena effectively are extremely important.</p><img src="https://counter.theconversation.com/content/40137/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vasu Misra receives funding from DOI, NOAA, USDA</span></em></p><p class="fine-print"><em><span>Mark Powell is Founder and President of HWind Scientific, which maintains the publicly available legacy NOAA HWind archive through an agreement with NOAA. HWind is a member of the American Meteorological Society, National Weather Association, American Weather and Climate Industry Association. Powell's current research is funded through the Cooperative Institute for Marine and Atmospheric Studies, which received funds from an interagency agreement between US Department of Energy and NOAA.</span></em></p>Everybody wants a quick shorthand for a storm’s damage potential. But the index we hear used most often isn’t the best option.Vasu Misra, Associate Professor of Meteorology, Florida State UniversityMark Powell, Atmospheric Scientist at the Center for Ocean-Atmospheric Prediction Studies , Florida State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/422352015-06-02T10:12:41Z2015-06-02T10:12:41ZTexas floods highlight need to reform key insurance program<p><em>This article is part of The Conversation’s series this month on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>Torrential storms have been coursing through much of Texas in recent days, prompting <a href="http://www.cnn.com/2015/05/31/us/severe-weather/index.html">massive flash flooding</a> that has swept away entire homes and left wakes of devastation. </p>
<p>Floodwaters continue to rise, so it will be days if not weeks before we can calculate the final costs, both in terms of life and property. But regardless, many will be turning to the federal government’s National Flood Insurance Program (NFIP) for help – it’s the only way to insure a property against damage from flooding. Unfortunately, it’s broke – and its very nature encourages development that makes each flood more damaging than the last. </p>
<p>While that doesn’t mean residents of Texas and elsewhere suffering from flood-related damages won’t get assistance, it does show that a reckoning is coming – either for policyholders or taxpayers. Without reforms to the NFIP that raise more money from premiums, its financial deficit will continue to widen and pile of debt will grow unchecked, eventually requiring a taxpayer-funded bailout to repair the damage. </p>
<p>Policyholders are likely unaware of the underlying finances, as the program has generally borrowed to pay off previous claims rather than raising rates.</p>
<p>Furthermore, the program encourages development of areas prone to flooding – while discouraging investment in modest protections – thereby leading to both costlier damages and environmental degradation. The point being that left largely alone, the floodplain provides essential protection against inland flooding and natural habitats for diverse wildlife. </p>
<p>Reforming the program to force property owners who choose to live in areas ripe for flooding to bear the real costs of ownership would help shore up the program and limit development on the floodplain, ensuring towns and cities throughout the US suffer less when waters rise. </p>
<h2>The government flood insurance market</h2>
<p>The NFIP, a government program that provides flood insurance to property owners across the United States, is more than <a href="http://www.gao.gov/highrisk/national_flood_insurance/why_did_study">US$20 billion in debt</a> and unlikely to ever pay off its creditors. </p>
<p>Under the program, the government requires anyone with a federally backed mortgage to purchase flood insurance if they live on a 100-year floodplain – about 16 million people, according to a <a href="http://stateofthecoast.noaa.gov/pop100yr/welcome.html">2010 estimate</a> from the National Oceanic and Atmospheric Administration. </p>
<p>Congress created the NFIP in the late 1960s after several large floods exposed homeowners and businesses without flood insurance to billions of dollars in losses. Insurance companies had not offered flood insurance through the private market since the 1920s. During the intervening years, virtually no insurance for flooding was available to homeowners, and typical home insurance policies did not cover flood damage. As a result, following a flood, homeowners were left to pay for damages themselves. </p>
<p>While the program has helped many flood victims, it also encourages development in coastal areas because the premiums are below what the risk-adjusted market rate would be and the US government essentially writes blank checks to cover losses. This ends up increasing the damages and loss of life from hurricanes and severe coastal storms. The program also encourages development in other flood basins, also increasing damage due to flooding.</p>
<p>Some areas have flood maps that dramatically understate the flood risk. The director of the Federal Emergency Management Agency (FEMA), which creates those maps, has said that only half are accurate and <a href="http://www.pianet.org/issues-of-focus/flood/2014/femasaysnfipfinancesunstable073114">has described</a> the NFIP’s finances as “unsustainable.” </p>
<p>And the latest report from the Government Accountability Office <a href="http://www.gao.gov/highrisk/national_flood_insurance/why_did_study">called</a> the program “by design, not actuarially sound.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83030/original/image-20150527-25095-10ybina.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The National Flood Insurance Program is billions in debt and encourages poor floodplain management.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/usgeologicalsurvey/2593495681/">U.S. Geological Survey/Flickr</a></span>
</figcaption>
</figure>
<h2>Not financially sound</h2>
<p>The NFIP is not a financially sound way to insure against floods and natural disasters because it collects in premiums far less than it pays out in claims. </p>
<p>The program extends subsidized rates to policyholders who meet certain conditions, including those who own property developed before 1974. The Federal Emergency Management Agency, the agency that manages the NFIP, also provides discounts to areas protected by levees or other physical barriers. </p>
<p>A <a href="http://www.gao.gov/new.items/d11670t.pdf">2011 GAO report</a> found more than one in five policyholders receive a subsidized policy, usually with a discount of 50% to 60%. Other policyholders partially pay for these subsidies through increased premiums on their own policies. </p>
<p>As a result, the NFIP is running a cumulative loss. To cover the losses, the NFIP borrows from the US Treasury, which in turn taps investors around the world to lend it more money, contributing to the national debt. At the close of 2014, the NFIP was $23 billion in the red.</p>
<p>Most of this is <a href="http://www.fema.gov/media-library-data/1408038596021-3354eb12e21447bc19f59d80a75a82fa/7-23-14%20-%20HFIAA%20Hearing_508.pdf">due to two large events</a>: Hurricane Katrina in 2005, which resulted in $17.5 billion in claims, and Superstorm Sandy in 2012, which cost $6.25 billion. </p>
<p>The NFIP has historically carried a much smaller debt. Prior to 2005, its debt <a href="http://www.washingtonpost.com/wp-srv/business/documents/health-science-NFIP-123110.pdf">peaked in 1997</a> at $917 million, an amount that was paid off by 2002. </p>
<p>While larger than other flood events, these storms represent the known peak flood risk. Accordingly, these peaks should be accounted for in assessing the flood risk and associated premiums. As global climate change affects weather patterns, hurricanes and overland heavy rainfall storms are increasing in intensity, and the associated claims paid by the NFIP are rising.</p>
<h2>Overdevelopment, environmental degradation</h2>
<p>The NFIP also ends up <a href="http://www.fema.gov/media-library-data/20130726-1602-20490-5762/nfip_eval_dei_summary_report.pdf">encouraging overdevelopment</a> on the floodplain. </p>
<p>The program subsidizes development there by transferring the costs away from current developers and property owners and to either future owners or taxpayers. Repeatedly flooded properties also receive an indirect subsidy through the frequent rebuilding costs, which are absorbed by the NFIP and not the property owner.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=195&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=195&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=195&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=244&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=244&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83174/original/image-20150527-4831-fe3gs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=244&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coastal development is at higher risk of flood and damages the natural protections against flood.</span>
<span class="attribution"><span class="source">Tyler Merbler/Flickr</span></span>
</figcaption>
</figure>
<p>Such development reduces overall flood protection. The floodplain, through beaches and barrier islands, helps absorb the impact of rising waters. Building immediately adjacent to water reduces the strength of these natural barriers. </p>
<p>Further, development removes <a href="http://www.dnrec.delaware.gov/swc/shoreline/pages/duneprotection.aspx">plant life and natural grasses that prevent erosion</a>. As beachfront erodes, its protective quality declines. Non-coastal areas are affected, too, when marshes and bogs are filled to provide arable or buildable land.</p>
<p>Returning these areas to their natural state and leaving them there would reduce overall flood damage. When coastal barriers and inland wetlands are able to absorb increase groundwater flow, nearby areas are naturally protected. Natural flood defenses will be increasingly important as the climate change causes sea levels to rise and increases the severity of storms.</p>
<h2>Short-lived effort at reform</h2>
<p>Even before Sandy, policymakers recognized the need to fix the NFIP’s finances. In 2012, Congress passed the <a href="https://www.fema.gov/media-library/assets/documents/31946">Biggert-Waters Flood Insurance Reform Act</a>, which required the NFIP to modernize the program by boosting premiums to levels that match the risks. Thus, the NFIP would move toward financial stability.</p>
<p>Biggert-Waters also mandated updates to the flood insurance rate maps that determine the cost of flood insurance for property owners, to more fairly and accurately allocate premiums. Rate changes <a href="http://www.gao.gov/assets/660/655734.pdf">were to be phased in</a>, with more than half of subsidized policies continuing to receive some level of discount.</p>
<p>But owners whose properties went from lower- to higher-risk status were not too pleased when their premiums increased and reeled when notified of the higher rates they’d have to pay. And many were simply unable to afford them. </p>
<p>As a result, these policyholders successfully pressured Congress in 2014 to <a href="http://www.insurancejournal.com/news/national/2014/03/26/324439.htm">roll them back</a>. The Homeowner Flood Insurance Affordability Act restored subsidies to grandfathered properties and capped the amount insurance premiums could increase. The Act also required FEMA to study flood insurance affordability. </p>
<h2>Congressional action necessary</h2>
<p>The risk transfer through reduced rates and the overdevelopment of the floodplain deliver a one-two punch to taxpayers and the environment unless reforms are made that require developers and owners to bear the true cost of building in those areas. </p>
<p>Biggert-Waters addressed these issues by requiring flood insurance policyholders to pay more of their share of the flood risk, but the law’s dilution means taxpayers are still left holding the bill after subsidizing property owners to remove vital flood protection along the coasts. </p>
<p>Congress still has the opportunity to stabilize the NFIP. Lawmakers should act soon to again allow the program to raise premiums to cover the true costs of insurance and gradually reduce the debt. </p>
<p>Further, the NFIP should cut program subsidies. By exposing property owners to the full cost of their building decisions, property owners would make better development decisions on the floodplain. That would leave us all a little better insured, against both inland flooding and getting socked with another bailout.</p><img src="https://counter.theconversation.com/content/42235/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James P Howard, II works for Eagle Ray, Inc., providing strategic transformation services to U.S. Citizenship and Immigration Services, a part of the United States Department of Homeland Security.</span></em></p>The National Flood Insurance Program – the only source for flood-prone property protection – is drowning in debt.James P. Howard II, Adjunct Faculty, Public Administration, University of BaltimoreLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/419182015-06-02T10:11:30Z2015-06-02T10:11:30ZBetter hurricane observation techniques over the decades make big storms less deadly<figure><img src="https://images.theconversation.com/files/83551/original/image-20150601-7003-1ardloh.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Luckily, we have more to go on now than just knowing the tracks of previous named storms.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Retired_Atlantic_hurricane_tracks.png">Titoxd</a></span></figcaption></figure><p><em>This article is part of The Conversation’s 2015 series on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>In September of 1900, the cyclone that would become the Great Galveston Hurricane passed from Cuba, across the Straits of Florida and over the Dry Tortugas. It then disappeared from forecasters’ maps into the Gulf of Mexico. Although its winds and waves tormented the steamships Pensacola and Louisiana, maritime radio reports lay a decade in the future.</p>
<p>As the storm approached, <a href="http://www.penguinrandomhouse.com/books/98112/isaacs-storm-by-erik-larson/">Isaac Cline</a>, the chief of the Weather Bureau’s Galveston office, had only the same clues that Columbus had learned to rely on <a href="https://global.oup.com/academic/product/divine-wind-9780195149418?q=Divine%20Wind&lang=en&cc=us">from the Taino people</a> 400 years before: a long-period swell from the east, winds and clouds moving from unusual directions. By sunrise on Sunday September 9, the storm had claimed <a href="http://www.hurricanescience.org/history/storms/1900s/Galveston/">as many as 8,000 lives</a>, the deadliest US natural disaster.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gJBd17uxF4o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Looking for bodies in Galveston after the hurricane.</span></figcaption>
</figure>
<p>Not so long ago, hurricanes used to make landfall essentially without warning. But over the past century or so, new observation technologies have allowed us to track these storms more effectively and thus make better predictions – and save lives.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83537/original/image-20150601-6981-137ub88.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Flights into the eye of the storm provided a whole new wealth of information.</span>
<span class="attribution"><span class="source">NOAA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Storms no longer come out of nowhere</h2>
<p>Landline telegraph reports and, after 1910, radio ship reports formed the observational basis of real-time forecasts until <a href="http://www.history.noaa.gov/stories_tales/surprise.html">Joseph Duckworth</a> flew a single-engine instrument-training airplane into the “Surprise” Hurricane of 1943. Once aviators realized they could penetrate to the centers of hurricanes and live, aircraft reconnaissance of hurricanes became routine. Observational tools were still primitive — visual estimation of wind direction and speed based on the appearance of the sea and extrapolation of surface pressures from altitudes of a few hundred feet.</p>
<p>The next year, the Weather Bureau attributed relatively light loss of life in New England during the Great Hurricane of 1944 to <a href="http://docs.lib.noaa.gov/rescue/mwr/072/mwr-072-09-0187.pdf">more accurate forecasts</a> thanks to aircraft observations. World War II brought other technological developments, particularly weather radar and widespread rawinsonde (weather balloon) observations. They increased the data collection area from the Earth’s surface to more than 50,000 feet up, albeit primarily over land.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83548/original/image-20150601-7000-wa5as6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Superfortress weather ship of the 53 Weather Reconnaissance Squadron landing at its base in England.</span>
<span class="attribution"><a class="source" href="http://en.wikipedia.org/wiki/File:Boeing_B-50_(WB-50D)_9261_MATS_Burtonwood_29.04.56_edited-2.jpg">RuthAS</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>By the 1950s, our modern forecasting system was in place. Aircraft scouted eastward across the Atlantic for developing tropical cyclones. Once a tropical storm (winds stronger than 40 mph) or hurricane (stronger than 75 mph) formed, airplanes would “fix” its center four times a day by flying inward perpendicular to the wind until they reached the calm at the center. They would record the strongest winds – based upon visual estimates or lowest <a href="http://dx.doi.org/10.1175/WAF-D-14-00121.1">extrapolated pressure</a> – as they flew in and out of the eye, and also the position and lowest pressure at the center.</p>
<p>With these data, forecasters could predict the hurricane’s motion a day into the future using subjective rules and, later, simple statistical models. They could also provide mariners and coastal residents with useful estimates of damaging winds, waves and rain – with some amount of warning.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=222&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=222&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=222&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=280&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=280&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83535/original/image-20150601-7000-kmbc4n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=280&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Satellites can track hurricanes from orbit and feed data back to ground-based forecasters.</span>
<span class="attribution"><span class="source">Hugh Willoughby</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Space-based observations</h2>
<p>Weather satellites were the next big advance. NASA’s <a href="http://science.nasa.gov/missions/tiros/">TIROS</a>, in 1960, flew in low-Earth (400 mile altitude) polar orbit that circled the globe in about an hour. These orbits passed near the poles, so the satellites crossed the equator going almost straight south or north. They typically passed near or over each point on the Earth’s surface twice a day as the planet rotated beneath them and transmitted both visible-light and infrared pictures. Quality was low, but the images revealed the presence of tropical cyclones throughout what had been the “oceanic data void” without any need for aircraft. The imagery supplied additional center locations to improve hurricane track forecasts, but more importantly, it greatly improved the forecasters’ “situation awareness.”</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=745&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=745&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=745&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=936&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=936&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83556/original/image-20150601-7003-r6t8o1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=936&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">GOES satellite observing Earth.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaaphotolib/5187402237">NOAA Photo Library</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These polar-orbiting satellites prepared the way for the geosynchronous satellites that became operational in 1974. They revolved in much higher (~22,000 mile) orbits above the equator. Their revolution period was the same as the Earth’s, so they stayed over the same geographical position, providing an ongoing stream of images at typical intervals of a half-hour. They were ideal for observation of tropical weather systems, but images of high-latitude features were severely foreshortened. By the end of the 20th century, geosynchronous satellite coverage extended around the globe. The <a href="http://www.goes.noaa.gov">NOAA GOES</a> satellites represent the current US realizations of polar-orbiting and geosynchronous satellites. </p>
<p>Also in the middle 1970s, <a href="http://dx.doi.org/10.1175/BAMS-87-9-1195">Vernon Dvorak</a> developed his scheme for estimating tropical cyclone intensity from visible-light images. In his scheme, the analyst recognized one of five scene types, made measurements of features’ sizes and arrangements, and combined the observed characteristics with recent intensity history to obtain estimated maximum wind speed. Along with satellite-based positions, Dvorak intensities are the cornerstones of 21st-century hurricane forecasting worldwide.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83542/original/image-20150601-6993-1buh6bv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Data collected by a flight into 1999’s Hurricane Floyd.</span>
<span class="attribution"><span class="source">NOAA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Measuring the variables</h2>
<p>The way to make forecasts ever more accurate is to feed them ever more detailed and reliable weather data. A number of technologies aim to do just that. </p>
<p>Scatterometers are active radars that scan conically below air- or spacecraft. The radar beams reflected from the sea provide estimates of surface wind directions and speeds. But the speeds are reliable only when the winds are weaker than hurricane force.</p>
<p>Stepped-frequency microwave radiometers (<a href="http://www.aoml.noaa.gov/hrd/project2005/sfmr.html">SFMRs</a>) are passive alternatives. The SFMR looks at the ocean’s surface at different wavelengths of light. By separating the microwave radiation emitted by rain from the apparent whitening of the water’s surface as the wind increases, the SFMR can estimate both rain rate and wind speed, but not direction.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iMvydih9rlM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Dropsondes away!</span></figcaption>
</figure>
<p>Dropsondes are instrument packages dropped on parachutes from aircraft and tracked by Global Positioning System. They measure in-situ wind, temperature, humidity and pressure between the aircraft and the Earth’s surface. The last observation before the dropsonde “splashes” contains a good estimate of the surface wind. Measurements of “steering currents” – winds around hurricanes that control their motion – made by dropsondes deployed by aircraft <a href="http://dx.doi.org/10.1175/2009MWR3090.1">flying around hurricanes</a> can <a href="http://cat.inist.fr/?aModele=afficheN&cpsidt=15034289">reduce track forecast errors</a> by more than 20%.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=642&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=642&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83540/original/image-20150601-6960-r8fwdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=642&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dropsondes provide another level of surface-level measurements while hurricanes are at sea.</span>
<span class="attribution"><span class="source">NOAA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>From the end of World War II until the mid-1980s, the US Air Force and Navy flew into both Atlantic hurricanes and Northeast Pacific typhoons. Then the US <a href="http://www.penguinrandomhouse.com/books/191117/hurricane-watch-by-dr-bob-sheets-and-jack-williams/9780375703904">terminated Pacific reconnaissance</a> completely, but retained a single Air Force Reserve reconnaissance squadron in the Atlantic. No other countries have taken up the mission because airplanes are expensive, while satellite observations, though generally less accurate, are readily available.</p>
<p>All of these sensor instruments can be fitted to autonomous aircraft (drones). Miniaturization of the instruments and the aircraft itself may make autonomous aircraft reconnaissance cost-effective outside of the Atlantic.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83560/original/image-20150601-6990-9m2bus.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricanes don’t catch us off-guard as they once did, as in the time of this 1865 woodcut.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaaphotolib/9672377448">NOAA Central Library Historical Collections</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Observations translate into lives saved</h2>
<p>Observations are the foundation of a prediction enterprise that includes statistical and physical models and the invaluable judgment of human forecasters. Today’s forecasts <a href="http://dx.doi.org/10.1061/(ASCE)NH.1527-6996.0000046">prevent</a> about 90% of the US hurricane-caused deaths you’d expect if technologies operated as they did in 1950 (scaling up for population). The <a href="https://members.agu.org/eweb/DynamicPage.aspx?Action=Add&ObjectKeyFrom=1A83491A-9853-4C87-86A4-F7D95601C2E2&WebCode=ProdDetailAdd&DoNotSave=yes&ParentObject=CentralizedOrderEntry&ParentDataObject=Invoice%20Detail&ivd_formkey=69202792-63d7-4ba2-bf4e-a0da41270555&ivd_cst_key=00000000-0000-0000-0000-000000000000&ivd_prc_prd_key=729BA523-9AE1-4507-804F-56EB1E3F9E48">economic value</a> of the saved lives is about US$1 billion annually, achieved at a cost of a small multiple of $100 million. The statistics for prevention of property damage are less impressive, largely because people can evacuate from deadly storm surge and freshwater flooding, whereas fixed property cannot. But ever-improving observation technologies allow us to prepare for what hurricane season dishes out.</p><img src="https://counter.theconversation.com/content/41918/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hugh Willoughby receives funding from National Science Foundation and National Oceanic and Atmospheric Administration. He also serves on the Florida Commission on Hurricane Loss Estimation Methodology.</span></em></p>We’re no longer caught off guard when hurricanes make landfall, the way people were into the early 1900s. Better communications, measurements and observations all feed into better forecasts and more warning.Hugh Willoughby, Distinguished Research Professor of Earth Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/407942015-06-01T06:00:31Z2015-06-01T06:00:31ZHurricane forecast accuracy is improving, but don’t overly focus on the skinny black line<figure><img src="https://images.theconversation.com/files/81279/original/image-20150511-19528-1twovqi.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hurricane path forecasts are good, but even the ‘cone of uncertainty’ doesn’t fully describe where the hazards could be.</span> <span class="attribution"><span class="source">National Hurricane Center</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><em>This article is part of The Conversation’s series this month on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>“Don’t focus on the skinny black line” was the trademark admonition of former National Hurricane Center (<a href="http://www.nhc.noaa.gov/">NHC</a>) director Max Mayfield dating back to the 1990s. It’s advice that media and residents of southwest Florida would have done well to heed when Hurricane Charley crossed Cuba in August 2004. Too much attention was paid to a track forecast depicting landfall near Tampa, and too few appreciated that Port Charlotte, only 70 miles to the south, was also under a hurricane warning. Although tropical cyclone forecasts had improved dramatically over the years, they were still far from perfect, as residents of Port Charlotte would soon find out.</p>
<h2>Is the storm headed for me?</h2>
<p>Highly visible successes, such as the dead-on track forecasts for 2003’s Hurricane Isabel, might have contributed to complacency ahead of Charley’s landfall the following year. And as it happens, tropical cyclone motion is a well-understood and relatively simple physical process: Storms are steered by the large-scale atmospheric currents that surround them.</p>
<p>For the past quarter-century, computer models have, for the most part, been able to effectively forecast a hurricane’s track. Using global measurements from a wide array of sensors, they take an estimate of the current state of the atmosphere and use certain physical laws to calculate forward in time to obtain the future position of the hurricane. Track forecasts have steadily improved as ever-increasing quantity and accuracy of atmospheric observations enable us to input more accurate initial conditions, and faster computers allow our numerical models to replicate the increasingly fine detail those observations provide.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">National Hurricane Center</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>This progress can be readily seen in the evolution of NHC’s “cone of uncertainty,” which is formed from circles that are expected to enclose the actual position of the storm two-thirds of the time. By this measure, the uncertainty in a hurricane’s track has decreased by nearly 40% over the decade since deadly Hurricane Katrina. The cone has gotten smaller as our forecast accuracy has improved. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82985/original/image-20150526-24754-zynyqs.GIF?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ten years later, we would have had more confidence in the Katrina’s expected path, as evidenced by the smaller ‘cone of uncertainty.’</span>
<span class="attribution"><span class="source">National Hurricane Center</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>While we at the NHC are pleased to see this improvement, of course, we continue to worry that highly successful track forecasts with recent storms such as Irene, Sandy and even 2015’s Ana may lead users to have developed unrealistic expectations. </p>
<h2>But how bad will it be?</h2>
<p>Forecasting hurricane intensity (the highest one-minute average wind associated with the storm), on the other hand, has proven to be more difficult. Readers likely have seen and remember numerous examples of forecast failures. The physics are far more complicated, involving features and processes on the smaller scale of miles or tens of miles, rather than the hundred- or thousand-mile-wide features that govern track.</p>
<p>In the early 1990s, numerical models that successfully forecast track were still hopelessly too coarse for intensity prediction. And there were nowhere near enough observations in and around the hurricane eyewall to get these models off to a good start, even if they <em>had</em> had sufficient resolution. With little objective guidance, forecasters got by on a combination of instinct and experience, until statistical models were developed that looked at how past storms in similar circumstances behaved. But even the statistical models were not as good as an experienced forecaster. It’s not surprising, then, that NHC’s official intensity errors were basically unchanged – locked in around 15 knots above or below the actual wind speeds for the average two-day error – through the decades of the ‘90s and the '00s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82988/original/image-20150526-24757-1m0dwc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The intensity forecast trend is going in the right direction… but can still use some improvement.</span>
<span class="attribution"><a class="source" href="http://www.nhc.noaa.gov/verification/figs/ALinerrtrd.jpg">National Hurricane Center</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The past few seasons, however, have seen a dramatic lowering of intensity forecast errors, particularly at two days out and longer. To some extent this has simply been good luck – strong wind shear and dry, sinking air have dominated the Atlantic basin in recent seasons and limited the numbers of strong and rapidly strengthening storms – and when storms stay weak, forecast errors tend to be low.</p>
<p>But NOAA’s Hurricane Forecast Improvement Project (<a href="http://www.hfip.org">HFIP</a>), a 10-year program now halfway completed, also deserves a share of the credit. HFIP has supported substantial investments in research, modeling and the development of tools for forecasters, all tightly focused on improving the objective guidance available to the National Hurricane Center.</p>
<p>The National Weather Service’s regional hurricane model, known as <a href="http://www.emc.ncep.noaa.gov/gc_wmb/vxt/">HWRF</a>, has been a particular target for HFIP-supported improvements. With increased resolution (the ability to “see” smaller and smaller atmospheric features), more accurate algorithms for estimating energy exchanges with the ocean and the handling of clouds, and more sophisticated ways of ingesting data from a hurricane’s inner core, the HWRF model has become skilled enough even to beat the NHC human forecasters in some retrospective tests. While it will likely require an active Atlantic hurricane season to truly assess how much progress we’ve made, we’re starting to see real advances. Unfortunately, HFIP <a href="http://www.corporateservices.noaa.gov/%7Enbo/fy15_bluebook/FY2015BudgetSummary-small.pdf#page=29">funding was cut</a> by more than half this year, putting future advances at risk.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/H7aa5TRQ8fE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Hurricane Irene headed from the Bahamas to North Carolina in 2011.</span></figcaption>
</figure>
<p>Nearly 20 years later, even as the science has progressed, Max Mayfield’s advice is still sound – don’t focus on the skinny black line! Forecasts are uncertain, and an appreciation of that uncertainty is essential to smart decision-making when hurricanes threaten. To help educate users, NHC has established a <a href="http://www.nhc.noaa.gov/verification/">web page dedicated to forecast accuracy</a>. Please drop by and have a look to see how well our forecasts measure up. And finally, even though NOAA and others are expecting a relatively quiet 2015 Atlantic hurricane season, remember: it takes only one bad storm in your neighborhood to make it a bad year for you.</p><img src="https://counter.theconversation.com/content/40794/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Franklin does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Forecasting successes can breed complacency in the general public. But all hurricane damage isn’t necessarily contained within the “cone of uncertainty.”James Franklin, Branch Chief Hurricane Specialist Unit at the National Hurricane Center, National Oceanic and Atmospheric AdministrationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/425362015-05-29T20:58:42Z2015-05-29T20:58:42ZIncreased typhoon intensity linked to ocean warming<figure><img src="https://images.theconversation.com/files/83427/original/image-20150529-15228-1gfphm0.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">More like these? Typhoon Haiyan in 2013. </span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p><em>This article is part of The Conversation’s series this month on hurricanes. You can read the rest of the series <a href="https://theconversation.com/us/topics/hurricanes-2015">here</a>.</em></p>
<p>Every year, typhoons over the western North Pacific – the equivalent to hurricanes in the North Atlantic – cause considerable damage in East and Southeast Asia. </p>
<p>Super Typhoon Haiyan of 2013, one of the strongest ocean storms ever recorded, devastated large portions of the Philippines and killed at least <a href="https://web.archive.org/web/20141006091212/http://www.ndrrmc.gov.ph/attachments/article/1177/Update%20Effects%20TY%20YOLANDA%2017%20April%202014.pdf">6,300 people</a>. It set records for the strongest storm at landfall and for the highest sustained wind speed over one minute, hitting 315 kilometers (194 miles) per hour when it reached the province of Eastern Samar.</p>
<p>The situation may get even worse. </p>
<p>Our new study of what controls the peak intensity of typhoons, published in the journal <a href="http://advances.sciencemag.org/content/1/4/e1500014-0"><em>Science Advances</em></a>, suggests that under climate change, storms like Haiyan could get even stronger and more common by the end of this century.</p>
<h2>Disentangling factors in typhoon peak intensity</h2>
<p>The lifetime peak intensity of a typhoon is the maximum intensity the storm reaches during its entire lifetime. It results from an accumulation of intensification, which is equivalent to speed being an accumulation of acceleration.</p>
<p>To better understand the variability and changes in typhoon peak intensity, we employed a novel approach by decomposing the peak intensity (akin to speed) into two components: intensification rate (akin to acceleration) and intensification duration (akin to time). These two components vary independently from each other from one year to another. We then separately explored the climate conditions that were most strongly associated with the year-to-year variations in these two components.</p>
<p>We examined various atmospheric and oceanic variables that might influence the rate of cyclone intensification. </p>
<p>We looked at atmospheric pressure, <a href="http://www.wunderground.com/education/shear.asp">vertical wind shear</a>, or the change in wind speed in one direction, and <a href="http://www.met.tamu.edu/class/ATMO151.hold/tut/hurr3.html">vorticity</a>, or the spin of the atmosphere. Surprisingly, we found that compared to those factors, ocean temperature most strongly correlated to the rate of cyclone intensification.</p>
<p>Specifically, how strongly and quickly a cyclone can grow depends on two oceanic factors: pre-storm sea surface temperature and the difference in temperature between the surface and subsurface. </p>
<p>A warmer sea surface generally provides more energy for storm development and thus favors higher intensification rates. </p>
<p>A large change in temperature from the surface to subsurface (ie, cooling with depth), however, can disrupt this flow of energy. That’s because strong winds drive turbulence in the upper ocean, which brings cold water up from below and cools the sea surface. Therefore, a smaller difference between surface and subsurface ocean temperature favors higher intensification rates.</p>
<p>On the other hand, the variations in the duration of typhoon intensification can be connected to sea surface temperatures associated with the naturally occurring phenomena known as El Nino-Southern Oscillation/Pacific Decadal Oscillation (ENSO/PDO). This is because in a positive phase of ENSO/PDO, warmer-than-normal sea surface temperatures over the central equatorial Pacific produce favorable atmospheric conditions for cyclone genesis near the equator and dateline. This allows developing typhoons to grow for a longer period of time over the warm water before reaching land or cold water.</p>
<p>In sum, our analyses reveal that the upper-ocean temperatures over the low-latitude western North Pacific influence typhoon intensification rates, and that sea surface temperatures over the central equatorial Pacific influence typhoon intensification duration. </p>
<p>We then quantified the relationships between typhoon peak intensity and these identified climatic factors – that is, local upper ocean temperatures and ENSO/PDO indices. </p>
<p>We concluded that the strong rise in typhoon peak intensity over the past 35 years or so (about five meters per second; equivalent to half a category in typhoon strength) can be mostly attributed to unusual local upper-ocean warming rates.</p>
<h2>Projecting typhoon peak intensity in a warming climate</h2>
<p>We analyzed the ocean temperature changes simulated by models from the fifth phase of the <a href="http://cmip-pcmdi.llnl.gov/">Coupled Model Intercomparison Project</a> (CMIP5), a model for studying interactions between ocean and the atmosphere. </p>
<p>We found that by year 2100, the temperature of the upper ocean will be more than 1.6 degrees Celsius higher than the baseline average of the 50-year period from 1955-2005 even under a moderate future scenario of greenhouse gas emissions. </p>
<p>The continued ocean warming provides more “fuel” for storm intensification. Using the statistical relationships built from observations, we projected that the intensity of typhoons in the western North Pacific will increase as much as 14% – nearly the equivalent to an increase of one category – by century’s end.</p><img src="https://counter.theconversation.com/content/42536/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wei Mei received funding from NASA Headquarters under the NASA Earth and Space Science Fellowship Program.</span></em></p>New analysis shows that warmer ocean temperatures in the Pacific are creating more intense typhoons.Wei Mei, Postdoctoral Scholar at Scripps Institution of Oceanography, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.